为什么Delta控制器中不使用速度环作为液压伺服位置环的内环

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slsheng 发表于 2018-3-26 18:25
北京思路盛对液压伺服位置闭环控制器没有速度闭环控制的理解：
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对于我来说微分就是电子阻尼，我大部分应用中都不用，微分对高频干扰由于太灵敏不是很好用

PEN

我给出了如何导出电机内部闭环传递函数的图片。电机传递函数比液压传动装置传递函数简单，因此更容易理解。

首先导出电机内部速度环的符号公式。然后内部回路用作执行器传递函数，但它必须通过乘以1 / s积分来将输出转换为位置。

然后使用外PI循环来控制内循环。结果是s ^ 0和s ^ 1的系数有两个增益。一个来自内部循环，另一个来自外部循环。如果内环增益改变，则应该改变相应的外环。

级联回路的另一个问题是，组合闭环传递函数的阶数比通过一个PID控制器而不是两个PI控制回路控制电机的阶数要高。当使用一个PID时，最终的闭环传递函数仅为三阶。当使用PID时，s ^ 0，s ^ 1和s ^ 2中只有一个增益。

I made picture showing how to derive the inner closed loop transfer function for a motor.  The motor transfer function is simpler than a hydraulic actuator transfer function so it is easier to understand.

First the symbolic formula for the motor's inner velocity loop is derived.  Then the inner loop is used as the actuator transfer function but it must be integrated by multiplying by 1/s to convert the output to position.

The outer PI loop is then used to control the inner loop.  The result is that the coefficients for s^0 and s^1 have two gains.   One from the inner loop and one from the outer loop.   If the inner loop gain is changed the corresponding outer loop should be changed.

Another problem with cascaded loops is that the order of the combined closed loop transfer funcion is one higher than if the motor was controlled by one PID controller instead of two PI control loops.  When one PID is used the final closed loop transfer function is only third order.  When a PID is used there is one and only one gain for s^0, s^1 and s^2.